FROM: alyceo@rconnect.com (JerryO) SUBJECT: Re: When to use 4WD vs Auto vs @WD DATE: 4 Feb 2002 22:57:21 -0800 ORGANIZATION: http://groups.google.com/ NEWSGROUPS: rec.autos.4x4 "JGP" wrote: > "The Ure" wrote: > > All wheel drive = Open Diff > > 4wheel Drive = Closed Diff > > Any questions? > > > Hmmmm. . . . so that makes mine both then? My centre diff is lockable so > sometimes its open and sometimes its closed. I get the impression from other > posters that AWD implies that not all the wheels are driven equally all the > time - mine always are all driven equally so I'm not sure it's ever AWD. I'm not as familiar as most others here, but it seems a little history should help. At least as I have heard: 1) Until 1972, the center differential was not used (at least not much). These are 'part time' systems of course. 2) Around 1973 (or 74) GM put in a lockable center differential, but no 2wd option. Gave it a name of 'full time 4 wheel drive' to indicate all 4 wheels were driven full time. 3) around 1990 ford and GM put 4 wheel drive in their mini-vans, but did not include a low range. They used 'AWD' to distinuish 'full time' (with a low range) from 'AWD' (without a low range). As you can tell I have left out a large list of other 4 wheel drives. Like Audi, subaru, toyota camry, ford tempo, and many more. 4) In the 1990's, the center differential was removed from some cars (AWD's) and computer controlled clutches were used to tranfer power from the primary driven wheels to the secondary set. In '98, GM made the minivan rear wheels primary and the front wheels only engage when slippage exists. Subaru, audi, honda crv, and others did this. However, from an operators point of view, the system resembled the previously defined 'AWD' and the AWD definition was CHANGED to include any system which worked without manual intervention. 5) Also appearing is the 2wd/fulltime system (I think fulltime systems always had a locked differential option). This system changes the definition of full time to a position 'which may be used full time' (as on any surface). My 2001 4runner is of this type. This gives me 2wd(high), 4wd with differential(high & low), and 4wd locked differential (high & low). I believe this system is now an option from most makers of trucks and large suv's (as those with a high and low range transfer case). From this, I think you can see that the manufacturer can and DOES give a name to the system according to the market for the product. If marketed for yuppies as a bad weather feature, it may be called AWD. If it is a heavy duty truck or suv unit, it may be called full time 4 wheel drive. On the other hand, it may have an entirely different name, or function entirely different with the same name. JerryO FROM: w.j.markerink@a1.nl (Willem-Jan Markerink) SUBJECT: Re: When to use 4WD vs Auto vs @WD DATE: Thu, 07 Feb 02 23:27:12 GMT NEWSGROUPS: rec.autos.4x4 In article , alyceo@rconnect.com (JerryO) wrote: >"JGP" wrote: >> "The Ure" wrote: >> > All wheel drive = Open Diff >> > 4wheel Drive = Closed Diff >> > Any questions? >> > >> Hmmmm. . . . so that makes mine both then? My centre diff is lockable so >> sometimes its open and sometimes its closed. I get the impression from other >> posters that AWD implies that not all the wheels are driven equally all the >> time - mine always are all driven equally so I'm not sure it's ever AWD. > >I'm not as familiar as most others here, but it seems a little history >should help. At least as I have heard: > >1) Until 1972, the center differential was not used (at least not >much). These are 'part time' systems of course. FYI: the first road-going 4x4 was a Dutch Spyker, in....1904....it had a center diff....:)) Not sure what the famous Mercedes G3 Jagdwagen had (with symmetrical 4 wheel steering it didn't need a center diff *offroad* (I doubt 4ws worked at higher speeds)), but the first serial center diff'ed vehicle was the Jensen FF, long before the Audi UrQuattro and Range Rover got it.... Lada Niva was also a rather early & unexpected adopter (1977), 7 years after the Range Rover (1970, a RR prototype existed in 1967)). >2) Around 1973 (or 74) GM put in a lockable center differential, but >no 2wd option. Gave it a name of 'full time 4 wheel drive' to indicate >all 4 wheels were driven full time. > >3) around 1990 ford and GM put 4 wheel drive in their mini-vans, but >did not include a low range. They used 'AWD' to distinuish 'full time' >(with a low range) from 'AWD' (without a low range). As you can tell I >have left out a large list of other 4 wheel drives. Like Audi, subaru, >toyota camry, ford tempo, and many more. > >4) In the 1990's, the center differential was removed from some cars >(AWD's) and computer controlled clutches were used to tranfer power >from the primary driven wheels to the secondary set. In '98, GM made >the minivan rear wheels primary and the front wheels only engage when >slippage exists. Subaru, audi, honda crv, and others did this. >However, from an operators point of view, the system resembled the >previously defined 'AWD' and the AWD definition was CHANGED to include >any system which worked without manual intervention. > >5) Also appearing is the 2wd/fulltime system (I think fulltime systems >always had a locked differential option). This system changes the >definition of full time to a position 'which may be used full time' >(as on any surface). My 2001 4runner is of this type. This gives me >2wd(high), 4wd with differential(high & low), and 4wd locked >differential (high & low). I believe this system is now an option from >most makers of trucks and large suv's (as those with a high and low >range transfer case). Nope. Neither Mercedes, Toyota/Land-Cruiser nor Land Rover have ever added 2wd to their center diff'ed vehicles. Simply because 2wd is a myth that only the US-customers wants, believing that it saves heaps of gas.... While it only ads complexity.... -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] FROM: "JGP" SUBJECT: Re: When to use 4WD vs Auto vs @WD DATE: Thu, 7 Feb 2002 23:38:20 -0000 ORGANIZATION: Very Little NEWSGROUPS: rec.autos.4x4 "Willem-Jan Markerink" wrote in message news:a3v1sn$1bifqo$1@ID-34205.news.dfncis.de... > >I'm not as familiar as most others here, but it seems a little history > >should help. At least as I have heard: > > > >1) Until 1972, the center differential was not used (at least not > >much). These are 'part time' systems of course. > > FYI: the first road-going 4x4 was a Dutch Spyker, in....1904....it had a > center diff....:)) > Not sure what the famous Mercedes G3 Jagdwagen had (with symmetrical 4 > wheel steering it didn't need a center diff *offroad* (I doubt 4ws worked > at higher speeds)), but the first serial center diff'ed vehicle was the > Jensen FF, long before the Audi UrQuattro and Range Rover got it.... > Lada Niva was also a rather early & unexpected adopter (1977), 7 years > after the Range Rover (1970, a RR prototype existed in 1967)). > Would you count the first Series I Land Rovers as they were 4WD all of the time even on road with a lockable 'free-wheel' device on the transferbox that prevented transmission windup from 1948? I believe it only lasted a year or so before the normal 2WD/4WD system was used instead. > >5) Also appearing is the 2wd/fulltime system (I think fulltime systems > >always had a locked differential option). This system changes the > >definition of full time to a position 'which may be used full time' > >(as on any surface). My 2001 4runner is of this type. This gives me > >2wd(high), 4wd with differential(high & low), and 4wd locked > >differential (high & low). I believe this system is now an option from > >most makers of trucks and large suv's (as those with a high and low > >range transfer case). > > Nope. Neither Mercedes, Toyota/Land-Cruiser nor Land Rover have ever added > 2wd to their center diff'ed vehicles. > Simply because 2wd is a myth that only the US-customers wants, believing > that it saves heaps of gas.... > While it only ads complexity.... > It saves about as much fuel as fitting free wheel hubs to part-time 4WD - ie absolutely none! JGP. FROM: w.j.markerink@a1.nl (Willem-Jan Markerink) SUBJECT: Re: When to use 4WD vs Auto vs @WD DATE: Fri, 08 Feb 02 01:33:33 GMT NEWSGROUPS: rec.autos.4x4 In article <1013125101.11380.0@eos.uk.clara.net>, "JGP" wrote: > >"Willem-Jan Markerink" wrote in message >news:a3v1sn$1bifqo$1@ID-34205.news.dfncis.de... >> > >> >I'm not as familiar as most others here, but it seems a little history >> >should help. At least as I have heard: >> > >> >1) Until 1972, the center differential was not used (at least not >> >much). These are 'part time' systems of course. >> >> FYI: the first road-going 4x4 was a Dutch Spyker, in....1904....it had a >> center diff....:)) >> Not sure what the famous Mercedes G3 Jagdwagen had (with symmetrical 4 >> wheel steering it didn't need a center diff *offroad* (I doubt 4ws worked >> at higher speeds)), but the first serial center diff'ed vehicle was the >> Jensen FF, long before the Audi UrQuattro and Range Rover got it.... >> Lada Niva was also a rather early & unexpected adopter (1977), 7 years >> after the Range Rover (1970, a RR prototype existed in 1967)). >> >Would you count the first Series I Land Rovers as they were 4WD all of the >time even on road with a lockable 'free-wheel' device on the transferbox >that prevented transmission windup from 1948? Sounds more like an auto-locker fitted in the center (with the front axle as the 'outside-wheel', allowed to freewheel in turns[*] than a true fulltime system (sending torque to all wheels all the time). [*] although an auto-locker works opposite when engine-braking; in that case the inside wheel is freewheeling, which would be the rear in a center-application....a lovely recipe for huge shockloads inbetween....:)) >I believe it only lasted a >year or so before the normal 2WD/4WD system was used instead. There is a very rare prototype of a full-time 40-series Land Cruiser known too....only surfaced once.... >> >5) Also appearing is the 2wd/fulltime system (I think fulltime systems >> >always had a locked differential option). This system changes the >> >definition of full time to a position 'which may be used full time' >> >(as on any surface). My 2001 4runner is of this type. This gives me >> >2wd(high), 4wd with differential(high & low), and 4wd locked >> >differential (high & low). I believe this system is now an option from >> >most makers of trucks and large suv's (as those with a high and low >> >range transfer case). >> >> Nope. Neither Mercedes, Toyota/Land-Cruiser nor Land Rover have ever added >> 2wd to their center diff'ed vehicles. >> Simply because 2wd is a myth that only the US-customers wants, believing >> that it saves heaps of gas.... >> While it only ads complexity.... >> >It saves about as much fuel as fitting free wheel hubs to part-time 4WD - ie >absolutely none! On some vehicles (Mitsu Pajero/Montero) there is also an argument of lesser engineering....2wd vibrates less than 4wd....8-)) -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!]